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Individual pyrrole molecules readily join together into larger molecules called polypyrroles. If polypyrroles form from pyrrole in the presence of zeolites, they do so by attaching to the zeolite either in lumps on the outer surface of the zeolite or in delicate chains within the zeolite's inner channels. When zeolite changes color from yellow to black, it means that on or in that zeolite polypyrroles have formed from pyrrole. Yellow zeolite free of any pyrrole was submerged in dissolved pyrrole. The zeolite, turned black even though no polypyrroles formed on its outer surface.

If the statements above are true, which one of the following must on the basis of them be true?


(A) Polypyrroles had already formed on or in the zeolite before it was submerged.

(B) Lumps of polypyrrole attached to the zeolite were responsible for its color change.

(C) At least some of the pyrrole in which the zeolite was submerged formed polypyrrole chains.

(D) None of the pyrrole in which the zeolite was submerged attached itself to the zeolite.

(E) Little, if any, of the pyrrole in which the zeolite was submerged reached the zeolite's inner channels.

My reasoning if it helps anyone:

The passage states that pyrrole molecules attach themselves on/in a zeolites to form a new compound called polypyrroles. A zeolite that has changed colors, means that there is some polypyrroles attached to it (either inside or outside). If a zeolite turns black, but there is no polypyrroles on the outside, it means it must have formed delicate chains within the zeolite's inner channels.

A) If this was true the zeolite would be black. Incorrect

B) The passage says no polypyrroles formed on the outside.

C) Correct, this MUST be true because there are only two ways for a zeolite to turn black. If it was not because of lumps of polypyrroles on the outside, it must be because of polypyrroles chains.

D) We know the zeolite turned black so this cannot be true

E) We know that the pyrrole must have reached the inner channels. That's the only way the zeolite turned black.


"The zeolite, turned black even though no polypyrroles formed on its outer surface". since it clearly mentions the OUTSIDE region ,
That means change in color happed because the pyrrole have reached the inner surface . thus, i feel option E is correct.
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Individual pyrrole molecules readily join together into larger molecules called polypyrroles. If polypyrroles form from pyrrole in the presence of zeolites, they do so by attaching to the zeolite either in lumps on the outer surface of the zeolite or in delicate chains within the zeolite's inner channels. When zeolite changes color from yellow to black, it means that on or in that zeolite polypyrroles have formed from pyrrole. Yellow zeolite free of any pyrrole was submerged in dissolved pyrrole. The zeolite, turned black even though no polypyrroles formed on its outer surface.

If the statements above are true, which one of the following must on the basis of them be true?

There are two ways that lead to change of color from yellow to black:
1. by attaching to the zeolite either in lumps on the outer surface of the zeolite
2. in delicate chains within the zeolite's inner channels

Thus, one or the other must have led to change in color and that must be true which we need to find out in the 5 choices.

(A) Polypyrroles had already formed on or in the zeolite before it was submerged. - WRONG. Goes against last sentence of the passage.

(B) Lumps of polypyrrole attached to the zeolite were responsible for its color change. - WRONG. Just reiterates what's there in the passage.

(C) At least some of the pyrrole in which the zeolite was submerged formed polypyrrole chains. - CORRECT.

(D) None of the pyrrole in which the zeolite was submerged attached itself to the zeolite. - WRONG. Again it goes against the passage otherwise the color would not have changed.

(E) Little, if any, of the pyrrole in which the zeolite was submerged reached the zeolite's inner channels. - WRONG. A philosophical reasoning. The lie nearest to the truth is hard to catch OR one can say its a shell game that is being played by this choice. Pyrrole reaching zeolite's inner channels is not enough for color change. What matters is whether polypyrroles are formed. This option does not tell us that. It was close though.

Answer C.
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